/Engine/Source/Runtime/Engine/Public/Net/OnlineEngineInterface.h
the stored nickname on the secondary/console OnlineSubsystem for a player with a given unique id
virtual bool GetPlayerPlatformNickname ( [UWorld](API\Runtime\Engine\Engine\UWorld) * World, int32 LocalUserNum, [FString](API\Runtime\Core\Containers\FString) & OutNickname )